The present invention relates to an assembly system for installing a roof module, especially a glass roof, in a roof opening of a vehicle body delivered on an assembly line.
The use of adhesive bonding techniques for fixing vehicle roofs in vehicle bodies is known from German documents DE 40 24 837 A1, DE 44 28 913 A1 and DE 195 02 019 C1. Such adhesive connections guarantee a high degree of crash-proofing, make it possible to compensate for tolerances and ensure that the external region of the body is sealed off from the passenger compartment in a watertight manner. German document DE 40 24 837 A1 also discloses a method for adhesively bonding a sliding roof module to a vehicle body. In this method, a cylindrical dose of adhesive is mechanically and automatically applied to the roof opening of the body. The sliding roof module is then lowered onto the body; the intention is that the cylindrical dose of adhesive will be compressed by the weight of the sliding roof module and a process-proof adhesive bonding of the roof module to the body will be achieved.
However, the method described in German document DE 40 24 837 A1 is time-consuming, as the body must be stationary during the application of the adhesive and the subsequent installation of the roof module until the adhesive has set. Moreover, any error occurring during application of the cylindrical dose of adhesive to the (previously finished) body involves high secondary costs: the body concerned has to be transferred out from the assembly line and carefully cleaned.
It is an object of the present invention to provide an assembly system for the installation of roof modules in vehicle bodies that avoids the abovementioned problems.
This object is achieved, according to the invention, by the claimed assembly system for installing a roof module in a roof opening of a vehicle body delivered on an assembly line. The assembly system includes an adhesive bonding station comprising a bonding robot for applying a cylindrical dose of adhesive to an inside of the roof module, an insertion station comprising an assembly robot for inserting the roof module provided with adhesive into the body, a first handling device for supplying the roof module to the adhesive bonding station and positioning it therein, a second handling device for removing the roof module from the adhesive bonding station and supplying it to the insertion station, and a control system for controlling the bonding robot, the assembly robot, and the handling devices. A roof module installation process is also claimed.
According to certain features of the invention, the cylindrical dose of adhesive is applied not to the vehicle body but to the roof module, which is subsequently positioned with high accuracy relative to the roof opening of the vehicle body and fixed therein. The associated assembly system comprises a bonding robot which applies a cylindrical dose of adhesive to the inside of the roof module. The roof module, provided with the adhesive, is passed by means of a handling device to an assembly robot, which inserts it with accurate positioning into the roof opening of a body delivered on an assembly line. A control system is provided to control and monitor the assembly operation.
Advantageous synchronization of the method steps of delivering the body on the assembly line on the one hand and applying the adhesive to the roof module on the other hand allows a substantial saving of time to result from the assembly system according to the invention as compared with conventional assembly methods. In contrast to the conventional methods, where the assembly system according to the invention is used, the body needs to be stationary only during the insertion of the roof module. The application of the cylindrical dose of adhesive to the roof module and the delivery of the roof module, provided with the adhesive, onto the assembly line can then take place before the point at which the body is transferred by the assembly line to the installation station.
Furthermore, where the assembly system according to the invention is used, errors in the application of the adhesive, such as smearing, premature setting of the adhesive, etc., are associated with much lower costs than in the case of conventional methods: in the event of defective application of the adhesive, the roof module in question is transferred out and at the same time a new roof module is provided with adhesive and inserted into the body. This is much less costly than the outward transfer of a contaminated body from the assembly line, cleaning and return to the assembly line that are necessary in the case of the conventional methods. The transferred roof module is cleaned and delivered again, without the assembly cycle or the assembly sequence of vehicle bodies being affected thereby.
The assembly system according to the invention permits fully automated assembly of the roof module even under the very cramped conditions in the immediate vicinity of an assembly line. The roof modules are advantageously delivered to the assembly system in load carriers that contain a plurality of roof modules. In a first step, they are separated and laid in templates with the inside upwards, so that they are already in an advantageous attitude for the application of the cylindrical dose of adhesive. To fix the roof modules in this attitude, the templates are expediently provided with automatic tensioning elements (e.g. suction cups which grip onto the outside of the roof module).
In order to deliver the roof modules laid in the templates to the adhesive bonding station, the assembly system comprises a first handling device. In order to avoid soiling of the joint regions of the roof modules during transfer and handling, the joint regions are in many cases covered with protective adhesive tapes directly after production of the roof module. Before the roof modules are delivered to the adhesive bonding station, these protective adhesive tapes have to be removed in order to expose the joint regions on the roof modules. For this purposes, a fully automated stripping device can be used. In that event, the protective adhesive tapes are expediently provided with projecting gripping loops; the stripping device grips these loops and strips off the protective adhesive tapes. Alternatively, the protective adhesive tapes can be stripped off manually. In that event, for ergonomic reasons, the roof module should be tilted in order to permit easy access to the protective adhesive tapes in all marginal areas of the roof module. Therefore, in this case, a pivoting device is provided by means of which the roof module fixed on the template is pivoted through approximately 80° about its longitudinal axis; after removal of the protective adhesive tapes by an operative, the roof module is pivoted back again into its initial position.
Immediately after the removal of the protective adhesive tapes, the roof module fixed on the template—with the inside upwards—is delivered to the adhesive bonding station where cylindrical doses of adhesive are applied to the joint regions. The adhesive is applied by means of a bonding robot, which travels along a pre-programmed bonding path with the aid of a CNC control system and in so doing deposits a cylindrical dose of adhesive on the joint regions by means of an adhesive nozzle. In order to ensure process-proof application of the cylindrical dose of adhesive, the adhesive nozzle is pressed by means of a spring against the roof module. The state of tension of the spring is continuously monitored, so that a defective contact between the adhesive nozzle and the roof is detected immediately and suitable counter-measures can be taken.
After application of the cylindrical dose of adhesive, the roof module is removed from the template by means of a further handling device and delivered to the assembly robot. For this purpose, the roof module is first advantageously tilted through 180° about its longitudinal axis in order to bring it in the installation position. In this attitude, the roof module is gripped by the assembly robot, by means of which the roof module is inserted into the roof opening of the body.
The insertion of the roof module into the body has to take place with extreme precision in order to ensure a high-quality visual impression made by the finished vehicle. In particular, the roof module must be oriented with high precision in the transverse direction of the body coordinate system relative to the roof opening in order to produce uniform gaps on both sides between the edges of the roof module and the roof struts of the body, into which clip-on trim strips are introduced in a subsequent assembly step. In order to guarantee such precise positioning of the roof module in the body, it is advantageous to install the roof module by means of an assembly tool which is mounted floatingly relative to the assembly robot. The tracking movement of the assembly robot corresponds to a permanently programmed CNC path; the floating mounting then permits compensation for tolerance-induced inaccuracies in the geometric dimensions and/or position of the roof module and/or of the body delivered on the assembly line, so that precise orientation of the roof module relative to the body can be achieved.
A precondition for this is that the roof module can be received in the assembly tool in a manner such that a high-precision orientation of the roof module relative to the assembly tool is ensured. For this purpose, the assembly tool is provided with (first) centering tools, whereby centering of the roof module relative to the assembly tool is achieved. Furthermore, the assembly tool is provided with additional (second) centering tools, by means of which accurate positioning of the assembly tool relative to the roof opening of the vehicle body is achieved. Thus, the roof module is gripped in a defined position relative to the assembly tool of the assembly robot, transferred to the body and inserted there in a defined position relative to the roof opening.
Once the roof module has been inserted into the roof opening of the body, the cylindrical dose of adhesive is compressed under the dead weight of the roof module. Experience suggests that it is extremely difficult here to dimension the quantity of adhesive applied or the distance between the regions of the roof module and of the roof opening to be bonded in such a way that the roof module sinks under its dead weight into the vehicle body in a process-proof manner and by exactly the right distance. In order to achieve a high-precision vertical orientation of the roof module relative to the roof opening, it is therefore advantageous to increase the size of the quantity of adhesive to be applied (or reduce the size of the distance between roof module and roof opening in the connection region) and to press the roof module with additional force while it is being inserted into the roof opening. For this purpose, the assembly tool is provided with fixing hooks which—after the roof module has been inserted into the vehicle body—engage into the window openings of the body and pull down the assembly tool to a level relative to the body roof that has been previously defined with high precision. In this manner, a reproducible vertical orientation of the roof module relative to the surrounding body roof can be achieved. The exertion of force by means of the fixing hooks is typically maintained for a few seconds until initial setting of the adhesive takes place and the roof module is fixed in that position.
In order to carry out a rapid quality control on the bodies—especially at the start of line production or in the event of equipment or design modifications—in relation to the size of the gaps between roof opening and roof module, it is advisable to provide the assembly system with a sensor system for detecting relevant measured parameters of the body and the roof module. Particularly advantageous is the use of optical sensors—for example, light-section sensors—by means of which a rapid contact-free detection and analysis of the gap sizes can be carried out before insertion of the roof module has ended; in the event of defective insertion, the position of the roof module can be adjusted immediately—i.e. before the adhesive has set—with the aid of the assembly tool.
The assembly system is particularly suitable for use on assembly lines on which different versions of motor vehicles are assembled, only selected motor vehicles needing to be provided with a roof module to be installed in the course of assembly whereas other vehicles have already been provided with a (welded-in) solid roof at the carcass stage. In order to ensure a smooth assembly of the different versions, it is advantageous to feed early information to the control system of the roof module assembly system on the points within the assembly sequence where vehicle bodies are present which have to be fitted with a roof module. This permits prompt commencement of the application of adhesive to the roof module to be inserted at the same time as the body in question is being delivered to the assembly line, so that the body reaches the assembly station at the same time as the adhesive-coated roof module. As a result, the time requirement associated with the bonding-in of the roof module is minimized. Furthermore, the adhesive is here prevented from being applied to the roof modules too early (or at the wrong time), which can result in setting of the adhesive before the roof module has been inserted into the body and hence increased reject rates or remedial work.
In an advantageous embodiment of the invention, the bodies are provided on the assembly line with electronically or optically readable mobile data storage media which contain information on the equipment of the particular vehicle body. The data from these mobile data storage media are read out with the aid of a sensor located at a suitable distance from the roof module assembly station at the edge of the assembly line and transmitted to the control system of the assembly system which analyses them to determine whether or not the installation of a glass roof is necessary. If a data set reaching the control system contains the requirement that a roof module is to be inserted, the control computer triggers the application of adhesive and the delivery of the roof module so that the roof module reaches the assembly station (as nearly as possible) simultaneously with the body.